The processing units of computers need to be kept cool so that they can operate within their performance specification. For computers used in vehicles this can be particularly challenging since, depending on the geographical region where the computer is used, the ambient temperature may be relatively high. Also, computing devices are being designed which consume more power for the same size of device. Typically, an in-vehicle computer generates waste heat at a rate of about 30 W and the case of the processor of the computer can only withstand a maximum temperature of about 100° C. The need for cooling generally increases the longer such a computer is being continuously used. In view of these requirements, which are becoming increasingly difficult to satisfy, there is a need for an improved efficiency heat sink to provide cooling of a processor unit in a mobile computer.
Heat sinks are known which are in the form of a cylindrical block having coolant channels formed between fins extending though the heat sink. Generally, the channels are formed so that the flow of coolant is generally from a single coolant inlet region and in one direction.
US-A-2002/0174980 describes a cylindrical block heat sink in which fins extend longitudinally through the heat sink to provide coolant flow generally in one direction. The fins change shape and are concentrated to provide improved cooling in a hotspot region, but the channels are generally of uniform width.